Google Inc. (GOOG.O: Quote, Profile, Research) on Wednesday debuted a test service called My Search History that analysts said is a move closer to personalized search, which is widely considered the Holy Grail for the Web search leader and its rivals. source

to use My Search History you must register at Google Accounts and maintain an active account. Ask Jeeves have had a search history tool for a while now and Yahoo! has My Yahoo! for various personalization effects, although Yahoo! seems more focused on providing news and blog feeds and the like. I think Yahoo! is betting on the abundance of information making subscribing to channels much more appealing than searching the web. I believe Yahoo! also allows you to subscribe to Yahoo! News feeds by keyword phrase.

Personalized search allows engines to better understand users to improve search quality and ad targeting. Whoever is branded as the best market solution on that front is going to make a bucket of cash, because keeping your search history and learning the user raises the barrier to switching search providers.

It makes it hard for another search service to be as relevant if you have tons of personal information already locked in a competing service. This data will be hard to export to other systems as well, as importing huge hunks of data will also allow marketers to import large volumes of spam.

I just briefly tested Google's service. It is fairly slick. You can quickly sign in or out and it adds minimal clutter to the Google home page.

From the link in the upper right corner you are brought to a new page. It shows a calender which color codes your search volume on the right side. The left side shows your searches for that day and the results you clicked on. The my history results that you click on also show up in the Google one box area when you search for similar terms using the regular search results.

Some privacy advocates would likely go nuts with this offering. It is all opt in though. I encourage everyone to sign in, search for seo, scroll past the Japanese stuff, and click on my listing.

Presumably some searchers may be able to build up a search history.
As they build it up it could build Google's trust in that user, which in turn could potentially allow Google to use that user feedback to verify search result relevancy.

I would not doubt this to do a bit more of globalizing SEO. Paying people in third world countries to randomly click certain sites. I am already building a search history today as a prospective SEO tool.